A conventional pump device and a conventional compressor device in which a piston moves within a cylinder in a linear manner includes a main body part which is provided with the cylinder and a linear actuator for driving the piston. A linear motor is used to reciprocate the piston in an axial direction as a driving part in the linear actuator (see, for example, Japanese Patent Laid-Open No. 2000-337725).
When the linear actuator is used as a drive source for a pump device or a compressor device, an ambient temperature at the time of the operation may rise to around 80 degrees Celsius. The movable body is disposed between the outer side laminated cores and the inner side laminated cores. The movable body includes a frame formed in a short cylindrical shape and the permanent magnet groups fixed at one end of the frame with an adhesive or the like. In this case, since the security of rigidity is difficult in the structure at the open end side of the permanent magnet groups, the open end of the permanent magnet groups may open on the outward side in the radial direction as the temperature rises, and thus, in the worst case, they may contact the outer side laminated cores to cause malfunction.